Additive for hydraulic cement mixes

Abstract

A hydraulic cement mix including hydraulic cement, aggregate, sufficient water to effect hydraulic setting of the cement, and an additive comprising a mixture of an alkali or alkaline earth or ammonium salt of thiocyanic acid, such as sodium, potassium, lithium, calcium or magnesium thiocyanate, and an alkanolamine, such as triethanolamine, the additive being present in an amount sufficient to increase rate of hardening, and the compressive strength of the hardened mix. Generally, the additive is present in a total amount of up to about 2.5% by weight based upon the weight of the cement, usually in an amount of between about 0.05% and about 2.55% by weight based upon the weight of the cement, preferably in an amount in the range of about 0.4% to about 0.6% by weight.

I claim: 
     
       1. A hydraulic cement mix comprising a hydraulic cement, aggregate in an amount of up to 80% by weight based upon the total weight of said cement mix, sufficient water to effect hydraulic setting of the cement, and an additive comprising a mixture of an alkali and/or alkaline earth or ammonium salt of thiocyanic acid in an amount of between 0.05% and 2.5% by weight based upon the weight of the cement and an alkanolamine in an amount of between 0.001% and 0.05% by weight based upon the weight of the cement, whereby the rate of hardening of said cement mix is accelerated and the early compressive strength of the hardened mix is increased. 
     
     
       2. A hydraulic cement mix in accordance with claim 1, wherein said hydraulic cement comprises portland cement. 
     
     
       3. A hydraulic cement mix in accordance with claim 1, wherein said salt of thiocyanate is present in an amount of between 0.5% and 1.5% by weight based upon the weight of the cement and said alkanolamine is present in an amount of between 0.01% and 0.04% by weight based upon the weight of the cement. 
     
     
       4. A hydraulic cement mix in accordance with claim 1, wherein said salt of thiocyanic acid is sodium thiocyanate. 
     
     
       5. A hydraulic cement mix in accordance with claim 1, wherein said salt of thiocyanic acid is potassium thiocyanate. 
     
     
       6. A hydraulic cement mix in accordance with claim 1, wherein said salt of thiocyanic acid is calcium thiocyanate. 
     
     
       7. A hydraulic cement mix in accordance with claim 1, wherein said salt of thiocyanic acid is magnesium thiocyanate. 
     
     
       8. A hydraulic cement mix in accordance with claim 1, wherein said aggregate is present in an amount of from 20% to 80% by weight. 
     
     
       9. A hydraulic cement mix in accordance with claim 1, wherein said alkanolamine comprises triethanolamine. 
     
     
       10. A process for accelerating the hardening of hydraulic cement mixes which include hydraulic cement, aggregate in an amount of up to 80% by weight based upon the total weight of said cement mix, and sufficient water to effect hydraulic setting of the cement, comprising incorporating an additive comprising a mixture of an alkali, alkaline earth or ammonium salt of thiocyanic acid in an amount of between 0.05% and 2.5% by weight based upon the weight of the cement and an alkanolamine in an amount of between 0.001% and 0.05% by weight based upon the weight of the cement, whereby the rate of hardening of said cement mix is accelerated and the early compressive strength of the hardened mix is increased. 
     
     
       11. A process in accordance with claim 10, wherein said hydraulic cement comprises portland cement. 
     
     
       12. A process in accordance with claim 10, wherein said salt of thiocyanate is present in an amount of between 0.5% and 1.5% by weight based upon the weight of the cement and said alkanolamine is present in an amount of between 0.01% and 0.04% by weight based upon the weight of the cement. 
     
     
       13. A process in accordance with claim 10, wherein said salt of thiocyanic acid is sodium thiocyanate. 
     
     
       14. A process in accordance with claim 10, wherein said salt of thiocyanic acid is potassium thiocyanate. 
     
     
       15. A process in accordance with claim 10, wherein said salt of thiocyanic acid is calcium thiocyanate. 
     
     
       16. A process in accordance with claim 10, wherein said salt of thiocyanic acid is magnesium thiocyanate. 
     
     
       17. A process in accordance with claim 10, wherein said aggregate is present in an amount of from 20% to 80% by weight. 
     
     
       18. A process in accordance with claim 10, wherein said alkanolamine comprises triethanolamine.